Report from 2014 student ASM student prize winner

The CRISPR-Cas ‘prokaryotic adaptive immune system' represents an intricate defence strategy allowing bacteria to protect themselves against invading genetic elements such as bacteriophages or plasmids. Through the acquisition of short segments of invading nucleic acid sequences into genomic CRISPR loci, this system provides a heritable genetic memory of previous exposure and, in combination with various CRISPR-associated (Cas) proteins, a means by which the bacteria can specifically recognise, target and eliminate the exogenous threat. In the past 10 years since the discovery of CRISPR-Cas systems, there has been a heavy focus on functionality; how the acquisition of genetic material occurs and how the system coordinates its targeted response. In contrast, very little is known how about how CRISPR-Cas systems are regulated. Of the limited literature available, there appears to be varied forms of control across the different CRISPR-Cas subtypes present in bacterial and archaeal species, indicating that a universal mode of regulation is perhaps unlikely.

After commencing my PhD studies in April 2014, my project has focused on elucidating this regulatory conundrum. To do so, we began work with Pectobacterium atrosepticum which is a plant pathogen which possessing a single Type I-F CRISPR-Cas system. Previous experiments in our lab had involved the application of a transposon mutagenesis which identified several candidate regulators of cas genes that I then examined in more detail. My work identified and confirmed an interacting network of regulators of CRISPR-Cas expression and highlighted a link to global regulators that sense the nutritional status of the cell. In addition, we revealed that mutating these regulators drastically affects both the acquisition and interference stages within CRISPR-Cas-mediated defence.

In November 2014, I attended the annual NZMS conference in Wellington which involved fascinating presentations from fellow scientists and students. I also entered into the student speaker competition where I was selected as first overall. My prize included a trip to the ASM conference in New Orleans the following May where I would have the opportunity to present a poster. Following the NZMS conference, I returned to University of Otago to continue my project and by late March we had submitted a paper which was accepted to NAR (Patterson et al, 2015). This was very satisfying and gave me a strong base from which I could structure my poster for ASM2015.

After departing from New Zealand on a long haul flight via LAX, my arrival into New Orleans came as a shock to the system. The night before I left it had been snowing in Dunedin yet when I stepped out of the airport I was met by a hot and humid summer day! I soon became used to my new surroundings and after a couple hours was immersing myself in southern culture. Exploring the French Quarter was a real treat with jazz musicians on every street corner and beautiful architecture proudly demonstrating the city’s cultural roots. Of course, I was also compelled to sample every piece of American cuisine I came across. If you’re a seafood fan, there is no better place than New Orleans to satisfy your hunger.

The ASM conference aimed to highlight the central role of microbes in the biosphere through sessions given by leading international scientists. It is the world’s largest annual microbiology meeting, which in 2014 had over 8,000 attendees! This year looked to be no exception and at the opening address I was stunned by the sheer number of scientists present (especially compared to the number I saw at the NZMS meeting). Here, ASM President Timothy Donohue provided an outline of the organisations future and three invited speakers presented their labs work. One particularly interesting talk regarded tracking the microbial response to the Deepwater Horizon oil spill in the Gulf of Mexico. After this, attendees were invited to the opening reception where we enjoyed light hors d’oeuvres, drinks and stimulating conversation.

Over the next few days, there were countless scientific seminars available for us to attend. Given the sheer number of presenters, it was impossible to see them all so you had to carefully study the programme and select the most interesting sessions accordingly. Given my diverse interests, I opted for a mixture of talks directly relevant to my field as well as those concerning exciting topics such as extremophiles and antimicrobials. Meet the speaker happy hours were an excellent chance to interact with presenters and network.

In addition to the various seminars on offer, I was able to attend workshops targeted at early career scientists which aimed to promote professional development. For example, one such session focused on high impact scientific writing and provided me with insights into ways I could express scientific ideas, findings and conclusions with greater clarity and impact. Considering the stage I am at in my career, these are exceptionally valuable tools. Another workshop I attended looked at the multitude of career choices available to young scientists. Here we learned not only about opportunities within a purely academic setting, but also alternatives ranging from industry through to clinical diagnostics.

The poster I presented, entitled “Regulation of the Type I-F CRISPR-Cas system of Pectobacterium atrosepticum”, was well received. In addition to casual passers-by, several people actively tracked me down as they were either involved in the CRISPR field or had a special interest in the topic. The questions posed by these participants offered valuable perspectives into our overall model and gave me several ideas for experiments to perform upon my return to NZ. One particular PhD student from America had actually read our paper beforehand and so was able to put forth informed comments and queries.

Overall, my time spent in New Orleans was a wonderful experience. I would like to express my sincere gratitude to the NZMS organisation for affording me the opportunity to attend ASM2015. It has allowed me to develop significantly as a scientist, gain insight into complimentary areas of microbial research, provided me with a platform to share my work and given me the chance to network with peers in my field.